- Cross-Coupling through Ag(I)/Ag(III) Redox Manifold
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In ample variety of transformations, the presence of silver as an additive or co-catalyst is believed to be innocuous for the efficiency of the operating metal catalyst. Even though Ag additives are required often as coupling partners, oxidants or halide scavengers, its role as a catalytically competent species is widely neglected in cross-coupling reactions. Most likely, this is due to the erroneously assumed incapacity of Ag to undergo 2e? redox steps. Definite proof is herein provided for the required elementary steps to accomplish the oxidative trifluoromethylation of arenes through AgI/AgIII redox catalysis (i. e. CEL coupling), namely: i) easy AgI/AgIII 2e? oxidation mediated by air; ii) bpy/phen ligation to AgIII; iii) boron-to-AgIII aryl transfer; and iv) ulterior reductive elimination of benzotrifluorides from an [aryl-AgIII-CF3] fragment. More precisely, an ultimate entry and full characterization of organosilver(III) compounds [K]+[AgIII(CF3)4]? (K-1), [(bpy)AgIII(CF3)3] (2) and [(phen)AgIII(CF3)3] (3), is described. The utility of 3 in cross-coupling has been showcased unambiguously, and a large variety of arylboron compounds was trifluoromethylated via [AgIII(aryl)(CF3)3]? intermediates. This work breaks with old stereotypes and misconceptions regarding the inability of Ag to undergo cross-coupling by itself.
- Demonti, Luca,Mézailles, Nicolas,Nebra, Noel,Saffon-Merceron, Nathalie
-
supporting information
p. 15396 - 15405
(2021/10/12)
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- Cathodic C-H Trifluoromethylation of Arenes and Heteroarenes Enabled by an in Situ-Generated Triflyltriethylammonium Complex
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While several trifluoromethylation reactions involving the electrochemical generation of CF3 radicals via anodic oxidation have been reported, the alternative cathodic, reductive radical generation has remained elusive. Herein, the first cathodic trifluoromethylation of arenes and heteroarenes is reported. The method is based on the electrochemical reduction of an unstable triflyltriethylammonium complex generated in situ from inexpensive triflyl chloride and triethylamine, which produces CF3 radicals that are trapped by the arenes on the cathode surface.
- Cantillo, David,Jud, Wolfgang,Kappe, C. Oliver,Maljuric, Snjezana
-
supporting information
(2019/10/08)
-
- 6-SHOGAOL DERIVATIVES AND ACTIVITIES THEREOF
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Derivatives of 6-shogaol are described herein. Also described herein are methods of preparing the derivatives, as well as methods of using the derivatives to activate Nrf2 and to treat diseases associated with inflammation and/or oxidative stress.
- -
-
Paragraph 0180; 0184
(2018/10/19)
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- Application of Silicon-Initiated Water Splitting for the Reduction of Organic Substrates
-
The use of water as a donor for hydrogen suitable for the reduction of several important classes of organic compounds is described. It is found that the reductive water splitting can be promoted by several metalloids among which silicon shows the best efficiency. The developed methodologies were applied for the reduction of nitro compounds, N-oxides, sulfoxides, alkenes, alkynes, hydrodehalogenation as well as for the gram-scale synthesis of several substrates of industrial importance.
- Gevorgyan, Ashot,Mkrtchyan, Satenik,Grigoryan, Tatevik,Iaroshenko, Viktor O.
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p. 375 - 382
(2018/06/04)
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- Preparation method of m-trifluoromethylphenol
-
The invention discloses a preparation method of m-trifluoromethylphenol. A preparation method of the m-trifluoromethylphenol comprises the following steps of enabling m-trifluoromethylphenol and alkali metal hydroxide and/or alkali metal alcohol to hydrolyze in an alcohol solvent under the condition of existence of a copper complex catalyst, and acidifying a reaction solution; the copper complex catalyst is selected from one or multiple of 8-copper hydroxyquinoline, 2-methyl-8-copper hydroxyquinoline, 4-methyl-8-copper hydroxyquinoline, copper acetate, and copper acetylacetonate. The preparation method has the advantages that the raw materials which can be easily purchased in industry are used for reacting, the technology is simple, the post-treatment is easy, the conditions are relativelymoderate, the pollution to environment is smaller, the m-trifluoromethylphenol with higher purity can be prepared at higher yield rate, the cost is low, and the industrialization application is realized. (The formula is shown in the description.).
- -
-
Paragraph 0065-0066; 0082; 0084; 0086
(2018/03/26)
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- Copper-Promoted Conversion of Aromatic Amines into Trifluoromethylated Arenes: One-Pot Sandmeyer Trifluoromethylation
-
A simple copper-promoted one-pot Sandmeyer trifluoromethylation of aromatic amines with Langlois’ reagent has been demonstrated. The reaction is performed in mild reaction conditions under an air atmosphere with good substrate scope and functional group compatibility. It provides an alternative and straightforward synthetic approach to access a variety of trifluoromethylated arenes.
- Hong, Jianquan,Wang, Guifu,Huo, Lianguang,Zheng, Changge
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supporting information
p. 1761 - 1767
(2017/09/06)
-
- The first nucleophilic C-H perfluoroalkylation of aromatic compounds via (arene)tricarbonylchromium complexes
-
The first nucleophilic perfluoroalkylation of arenes is based on the arene π-system activation via (η6-arene)tricarbonylchromium complexes. Perfluoroalkyl anions generated from Me3SiRF and a fluoride ion source [Me4N]F exclusively attack the arene ligand under mild conditions. The formed negatively charged analogs of Meisenheimer adducts readily undergo a one-pot oxidation to perfluoroalkyl arenes.
- Kirij, Natalia V.,Filatov, Andrey A.,Khrapach, Gleb Yu.,Yagupolskii, Yurii L.
-
supporting information
p. 2146 - 2149
(2017/02/19)
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- Phosphovanadomolybdic acid catalyzed direct C-H trifluoromethylation of (hetero)arenes using NaSO2CF3 as the CF3 source and O2 as the terminal oxidant
-
A direct C-H trifluoromethylation of (hetero)arenes using NaSO2CF3 (Langlois' reagent) as the CF3 source and O2 as the terminal oxidant has been developed. In the presence of catalytic amounts of phosphovanadomolybdic acids, such as H6PV3Mo9O40, various kinds of substituted benzenes and heteroaromatic compounds could be converted into the corresponding trifluoromethylated products.
- Li, Chifeng,Suzuki, Kosuke,Yamaguchi, Kazuya,Mizuno, Noritaka
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supporting information
p. 1417 - 1420
(2017/02/23)
-
- Isolation and characterization of copper(III) trifluoromethyl complexes and reactivity studies of aerobic trifluoromethylation of arylboronic acids
-
The isolation, characterization and reactivity of transition metal trifluoromethyl complexes are fundamental and challenging topics in trifluoromethylation chemistry. We report herein the synthesis and isolation of two new complexes [(phen)CuI(PPh3)2]+[CuIII(CF3)4]- (2) and (phen)CuIII(CF3)3 (3) as well as a known complex (bpy)CuIII(CF3)3 (4) at room temperature. 2 and 3 have been fully characterized using 1H, 19F, 31P NMR, elemental analyses and X-ray crystallography. Reactivity studies indicate that 2 is unreactive toward arylboronic acids. In contrast, 3 and 4 can react with various aryl and heteroaryl boronic acids to deliver trifluoromethylated arenes in good to quantitative yields under mild conditions. The presence of a fluoride additive in DMF under aerobic conditions is crucial to these reactions. This study provides fundamental information about the structure and reactivity of elusive Cu(iii) trifluoromethyl complexes that have been proposed as relevant reactive intermediates in many trifluoromethylation reactions.
- Zhang, Song-Lin,Bie, Wen-Feng
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p. 70902 - 70906
(2016/08/05)
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- Synthesis, evaluation, and metabolism of novel [6]-shogaol derivatives as potent Nrf2 activators
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Oxidative stress is a central component of many chronic diseases. The Kelch-like ECH-associated protein 1 (Keap1)-nuclear factor erythroid 2 p45-related factor 2 (Nrf2) system is a major regulatory pathway of cytoprotective genes against oxidative and electrophilic stress. Activation of the Nrf2 pathway plays crucial roles in the chemopreventive effects of various inducers. In this study, we developed a novel class of potent Nrf2 activators derived from ginger compound, [6]-shogaol (6S), using the Tg[glutathione S-transferase pi 1 (gstp1):green fluorescent protein (GFP)] transgenic zebrafish model. Investigation of structure-activity relationships of 6S derivatives indicates that the combination of an α,β-unsaturated carbonyl entity and a catechol moiety in one compound enhances the Tg(gstp1:GFP) fluorescence signal in zebrafish embryos. Chemical reaction and in vivo metabolism studies of the four most potent 6S derivatives showed that both α,β-unsaturated carbonyl entity and catechol moiety act as major active groups for conjugation with the sulfhydryl groups of the cysteine residues. In addition, we further demonstrated that 6S derivatives increased the expression of Nrf2 downstream target, heme oxygenase-1, in both a dose- and time-dependent manner. These results suggest that α,β-unsaturated carbonyl entity and catechol moiety of 6S derivatives may react with the cysteine residues of Keap1, disrupting the Keap1-Nrf2 complex, thereby liberating and activating Nrf2. Our findings of natural product-derived Nrf2 activators lead to design options of potent Nrf2 activators for further optimization.
- Zhu, Yingdong,Wang, Pei,Zhao, Yantao,Yang, Chun,Clark, Anderson,Leung, TinChung,Chen, Xiaoxin,Sang, Shengmin
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p. 243 - 254
(2016/04/20)
-
- DBU-Promoted Trifluoromethylation of Aryl Iodides with Difluoromethyltriphenylphosphonium Bromide
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DBU-promoted trifluoromethylation of aryl iodides with difluoromethyltriphenylphosphonium bromide (DFPB) in the presence of copper source is described. In this transformation, DBU not only acts as base to deprotonate the difluoromethyl group in DFPB to generate difluoromethylene phosphonium ylide Ph3P+CF2-, but also converts the difluorocarbene generated from ylide Ph3P+CF2- into trifluoromethyl anion, finally resulting in the trifluoromethylation of aryl iodides. The reactions proceeded smoothly to afford expected products in moderate to good yields.
- Wei, Yun,Yu, Liuying,Lin, Jinhong,Zheng, Xing,Xiao, Jichang
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p. 481 - 484
(2016/06/01)
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- Trifluoromethylation of haloarenes with a new trifluoro-methylating reagent Cu(O2CCF2SO2F)2
-
A new trifluoromethylating reagent Cu(O2CCF2SO2F)2, which easily decomposes to generate active CuCF3 species in DMF at room temperature, has been conveniently prepared from inexpensive starting materials on a large scale. This new reagent can be applied to efficiently trifluoromethylate a variety of haloarenes under mild conditions, providing good-to-excellent yields of the desired products.
- Zhao, Gang,Wu, Hao,Xiao, Zhiwei,Chen, Qing-Yun,Liu, Chao
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p. 50250 - 50254
(2016/06/15)
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- Palladium-Catalyzed Trifluoromethylation of (Hetero)Arenes with CF3Br
-
The CF3 group is an omnipresent motif found in many pharmaceuticals, agrochemicals, catalysts, materials, and industrial chemicals. Despite well-established trifluoromethylation methodologies, the straightforward and selective introduction of such groups into (hetero)arenes using available and less expensive sources is still a major challenge. In this regard, the selective synthesis of various trifluoromethyl-substituted (hetero)arenes by palladium-catalyzed C-H functionalization is herein reported. This novel methodology proceeds under comparably mild reaction conditions with good regio- and chemoselectivity. As examples, trifluoromethylations of biologically important molecules, such as melatonin, theophylline, caffeine, and pentoxifylline, are showcased.
- Natte, Kishore,Jagadeesh, Rajenahally V.,He, Lin,Rabeah, Jabor,Chen, Jianbin,Taeschler, Christoph,Ellinger, Stefan,Zaragoza, Florencio,Neumann, Helfried,Brückner, Angelika,Beller, Matthias
-
supporting information
p. 2782 - 2786
(2016/02/27)
-
- METHOD FOR PREPARATION OF FLUORO, CHLORO AND FLUOROCHLORO ALKYLATED COMPOUNDS BY HOMOGENEOUS CATALYSIS
-
The invention discloses a method for preparation of fluoro, chloro and fluorochloro alkylated compounds by homogeneous Pd catalyzed fluoro, chloro and fluorochloro alkylation with fluoro, chloro and fluorochloroalkyl halides in the presence of di(1-adamantyl)-n-butylphosphine and in the presence of 2,2,6,6-tetramethylpiperidine 1-oxyl.
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Page/Page column 15; 16; 17
(2016/06/01)
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- Mechanism of trifluoromethylation of aryl halides with CuCF3and the ortho effect
-
A combined experimental (radical clock, kinetic, Hammett) and computational (DFT, MM) study of the trifluoromethylation reaction of aryl halides with CuCF3 reveals a nonradical mechanism involving Ar-X oxidative addition to the Cu(I) center as the rate determining step. The reaction is second order, first order in each reactant with ΔG? ≈ 24 kcal/mol for PhI (computed ΔG? = 21.9 kcal/ mol). An abrupt change in the gradient on the Hammett plot of log(kR/ kH) versus σp for 11 p-RC6H4I substrates produces two correlations (ρ = +0.69 and +1.83), which is temptingly suggestive of two different reaction pathways. Only one mechanism is operational, however, as advocated by a single linear correlation with σp- (ρ = +0.91), analysis of the experimental ρ values, close similarity of the transition states varying in R and displaying clear signs of -M interactions, and excellent reproduction of the plot by DFT. The long-known yet previously uncomprehended ortho effect has been quantified, for the first time, using the reaction of CuCF3 with a series of o-RC6H4Br: R(kR/kH) = H (1) 2Me (850) 2 (4300) 2H (150 000). With minor contributions from electronic factors, the ortho effect is largely determined by (i) the stabilizing coordination of the o-substituent to Cu in the transition state with the Cu?O distance varying directly with the barrier and (ii) the steric bulk of the o-substituent that raises the ground state free energy of the haloarene (Go ortho - Go H or Go ortho - Go para) by inflicting molecular strain and consequently weakening the Ar-X bond.
- Konovalov, Andrey I.,Lishchynskyi, Anton,Grushin, Vladimir V.
-
supporting information
p. 13410 - 13425
(2015/03/30)
-
- Copper-mediated trifluoromethylation of aryl-, heteroaryl-, and vinyltrifluoroborates with Langlois' reagent
-
An effortless and realistic procedure for the copper-mediated trifluoromethylation of aryl-, heteroaryl- and vinyltrifluoroborates with CF3 radicals generated from NaSO2CF3 and tert-butyl hydroperoxide (TBHP) is presented. The developed method produces trifluoromethyl arenes and -alkenes in good to excellent yields and a wide range of electronically and structurally diverse substrates are tolerated.
- Dubbaka, Srinivas Reddy,Salla, Manohar,Bolisetti, Raghu,Nizalapur, Shashidhar
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p. 6496 - 6499
(2014/02/14)
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- Trifluoromethylation of aryl and heteroaryl halides with fluoroform-derived CuCF3: Scope, limitations, and mechanistic features
-
Fluoroform-derived CuCF3 recently discovered in our group exhibits remarkably high reactivity toward aryl and heteroaryl halides, performing best in the absence of extra ligands. A broad variety of iodoarenes undergo smooth trifluoromethylation with the ligandless CuCF3 at 23-50 C to give the corresponding benzotrifluorides in nearly quantitative yield. A number of much less reactive aromatic bromides also have been trifluoromethylated, including pyridine, pyrimidine, pyrazine, and thiazole derivatives as well as aryl bromides bearing electron-withdrawing groups and/or ortho substituents. Only the most electrophilic chloroarenes can be trifluoromethylated, e.g., 2-chloronicotinic acid. Exceptionally high chemoselectivity of the reactions (no side-formation of arenes, biaryls, and C2F5 derivatives) has allowed for the isolation of a large number of trifluoromethylated products in high yield on a gram scale (up to 20 mmol). The CuCF3 reagent is destabilized by CuX coproduced in the reaction, the magnitude of the effect paralleling the Lewis acidity of CuX: CuCl > CuBr > CuI. While SNAr and SRN1 mechanisms are not operational, there is a well-pronounced ortho effect, i.e., the enhanced reactivity of ortho-substituted aryl halides 2-RC6H4X toward CuCF3. Intriguingly, this ortho-effect is observed for R = NO2, COOH, CHO, COOEt, COCH3, OCH3, and even CH3, but not for R = CN. The fluoroform-derived CuCF3 reagent and its reactions with haloarenes provide an unmatched combination of reactivity, selectivity, and low cost.
- Lishchynskyi, Anton,Novikov, Maxim A.,Martin, Eddy,Escudero-Adan, Eduardo C.,Novak, Petr,Grushin, Vladimir V.
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p. 11126 - 11146
(2013/12/04)
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- Catalytic decarboxylative fluorination for the synthesis of Tri- and difluoromethyl arenes
-
Treatment of readily available α,α-difluoro- and α-fluoroarylacetic acids with Selectfluor under Ag(I) catalysis led to decarboxylative fluorination. This operationally simple reaction gave access to tri- and difluoromethylarenes applying a late-stage fluorination strategy. Translation to [18F]labeling is demonstrated using [ 18F]Selectfluor bis(triflate), a reagent affording [ 18F]tri- and [18F]difluoromethylarenes not within reach with [18F]F2.
- Mizuta, Satoshi,Stenhagen, Ida S.R.,O'Duill, Miriam,Wolstenhulme, Jamie,Kirjavainen, Anna K.,Forsback, Sarita J.,Tredwell, Matthew,Sandford, Graham,Moore, Peter R.,Huiban, Mickael,Luthra, Sajinder K.,Passchier, Jan,Solin, Olof,Gouverneur, Véronique
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p. 2648 - 2651
(2013/07/11)
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- Fluoroform-derived CuCF3 for low-cost, simple, efficient, and safe trifluoromethylation of aryl boronic acids in air
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Easy does it: Aryl boronic acids undergo smooth and selective trifluoromethylation with low-cost fluoroform-derived CuCF3 in DMF in non-dried air. The reaction occurs under mild conditions (1 atm, room temperature), exhibits unprecedented funct
- Novak, Petr,Lishchynskyi, Anton,Grushin, Vladimir V.
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supporting information; experimental part
p. 7767 - 7770
(2012/08/29)
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- A convenient and practical synthesis of anisoles and deuterated anisoles by palladium-catalyzed coupling reactions of aryl bromides and chlorides
-
Synthesis of anisole: Aryl and heteroaryl halides undergo selective C-O cross-coupling reactions with methanol in the presence of a Pd(OAc) 2/L3 catalyst system. The corresponding ethers were obtained under mild conditions in good yields. The catalytic methodology was also used for the synthesis of labeled deuterated anisoles in good yields (see scheme). Copyright
- Gowrisankar, Saravanan,Neumann, Helfried,Beller, Matthias
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supporting information; experimental part
p. 2498 - 2502
(2012/03/27)
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- Silver-mediated trifluoromethylation of arenes using TMSCF3
-
The silver-mediated C-H trifluoromethylation of aromatic substrates using TMSCF3 is described. The development, optimization, and scope of these transformations are reported. AgCF3 intermediates are proposed.
- Ye, Yingda,Lee, Shin Hee,Sanford, Melanie S.
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supporting information; experimental part
p. 5464 - 5467
(2011/12/05)
-
- Synthesis of novel structurally simplified estrogen analogues with electron-donating groups in ring A
-
A library of 25 novel estrogen analogues were prepared in five to eight steps from mostly commercially available substituted anisoles via bromination, formylation, Corey-Fuchs reaction, elimination, and Sonogashira reaction. Georg Thieme Verlag Stuttgart.
- Tietze, Lutz F.,Vock, Carsten A.,Krimmelbein, Ilga K.,Nacke, Linda
-
experimental part
p. 2040 - 2060
(2009/12/27)
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- Copper-carbene complexes and their use
-
The invention relates to copper-carbene complexes, to a process for preparing them and to their use in catalytic coupling reactions.
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-
Page/Page column 6
(2010/02/08)
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- One-step preparation of some 3-substituted anisoles
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A one-step preparation of 3-bromoanisole, 3-chloroanisole, and 3-trifluoromethylanisole from the corresponding 3-substituted nitrobenzenes is carried out by nucleophilic aromatic substitution of the nitro group with sodium or potassium methoxide, employing an effective amount of a phase-transfer catalyst (PTC), in a medium of a nonpolar aprotic solvent, under aerobic conditions, at a temperature of 50-65°C. The alkali methoxide used can be a pre-prepared solid, or it can be prepared in situ from the alkali hydroxide and methanol. The methoxydenitration proved to be very sensitive to the type of PTC. The effect of the solvent on the reaction is discussed. The targeted anisoles are obtained in yields of more than 80% and purities of greater than 99%.
- Zilberman, Joseph
-
p. 303 - 305
(2013/09/06)
-
- Direct Perfluoroalkylation of Aromatic and Heteroaromatic Compounds with Perfluoroalkanesulfonyl Chlorides Catalysed by a Ruthenium(II) Phosphine Complex
-
The perfluoroalkylation of aromatic and heteroaromatic compounds by perfluoroalkanesulfonyl chlorides 1 has been investigated in the presence of a ruthenium(II) phosphine complex.The reaction of compounds 1 with substituted benzenes or thiophenes proceeded smoothly with extrusion of sulfur dioxide at 120 deg C to give corresponding perfluoroalkylated compounds in good yield.No expected perfluoroalkylated product was obtained in the reaction of compounds 1 with pyrrole; however, 1-trimethylsilyl- and 1-triisopropylsilyl-pyrrole were regioselectively perfluoroalkylated at their 2- and 3-position, respectively.
- Kamigata, Nobumasa,Ohtsuka, Takeshi,Fukushima, Takamasa,Yoshida, Masato,Shimizu, Toshio
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p. 1339 - 1346
(2007/10/02)
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- An Efficient Electrochemical Trifluoromethylation of Aromatic Halides with Bromotrifluoromethane and a Sacrificial Copper Anode
-
The electrochemical cross-coupling of bromotrifluoromethane with aromatic or heteroaromatic iodides and bromides is successfully achieved in a one-compartment electrolysis cell fitted with a sacrificial copper anode.
- Paratian, J. M.,Sibille, S.,Perichon, J.
-
-
- TRIFLUOROMETHYLATION OF AROMATIC COMPOUNDS WITH BIS(TRIFLUOROACETYL) PEROXIDE
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Bis(trifluoroacetyl) peroxide was found to be thermally stable, and trifluoromethylation of aromatic compounds was studied using this peroxide.Trifluoromethylation of electron-rich benzenes, furan, thiophene, or their benzo derivatives proceeded with the peroxide in moderate to high yields.
- Sawada, Hideo,Nakayama, Masaharu,Yoshida, Masato,Yoshida, Tatsuro,Kamigata, Nobumasa
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p. 423 - 431
(2007/10/02)
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- Reactions of Perfluoroalkanesulfonyl Chlorides with Aromatic Compounds Catalyzed by a Ruthenium(II) Complex
-
The reactions of perfluoroalkanesulfonyl chlorides with aromatic compounds in the presence of a catalytic amount of dichlorotris(triphenylphosphine)ruthenium(II) were found to give perfluoroalkylated compounds in good yield.
- Kamigata, Nobumasa,Fukushima, Takamasa,Yoshida, Masato
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p. 649 - 650
(2007/10/02)
-
- Photochemical Trifluoromethylation of Some Aromatic and Heteroaromatic Compounds with Trifluoromethyl Bromide
-
The photochemical introduction of trifluoromethyl group with CF3Br in aromatic and heteroaromatic rings was investigated for 9 compounds.Naphthalene, anthracene, anisole, N,N-dimethylaniline, ferrocene, benzothiophene, isoquinoline, and N-methylpyrrole gave trifluoromethylated products in 6.5-100percent yields.In one step from uracil, a pharmacologically important 5-trifluoromethyluracil can be synthesized by this method in 11percent yield.Based on the mechanistic study carried out for the naphthalene-CF3Br-CH3CN system, the reaction is found to proceed via the electron transfer from an excited singlet state of naphthalene to CF3Br.
- Akiyama, Takeo,Kato, Kohji,Kajitani, Masatsugu,Sakaguchi, Yoshio,Nakamura, Junko,et al.
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p. 3531 - 3538
(2007/10/02)
-
- Substituent effects on the meta photocycloaddition of arenes to alkenes
-
The meta photocycloaddition of cyano- and (trifluoromethyl)-substituted anisoles to cyclopentene has been investigated and the product ratios are shown to be compatible with a polar mechanism.The photochemical and thermal interconversions of the major adducts from 3-cyanoanisole and cyclopentene have also been investigated.
- Osselton, E. M.,Lempers, E. L. M.,Eyken, C. P.,Cornelisse, J.
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p. 171 - 175
(2007/10/02)
-
- Studies on Organic Fluorine Compounds. Part 27. Abnormal Reactions in the Trifluoromethylation of Aromatic Compounds with Trifluoromethyl Iodide and Copper Powder
-
Reaction of 3-bromobenzofuran with trifluoromethyl iodide and copper powder in pyridine gave 2-(trifluoromethyl)-, 2- and 3-(pentafluoroethyl)-, and 2,3-bis(trifluoromethyl)-benzofuran, as well as the expected product, 3-(trifluoromethyl)benzofuran.Bromoanisole also gave (trifluoromethyl)anisole and (pentafluoroethyl)anisole, but introduction of the perfluoroalkyl group occurred at the position originally occupied by the bromine.Formation of pentafluoroethyl compounds is explained by decomposition of trifluoromethylcopper to cuprous fluoride and difluorocarbene, which can then react with a further molecule of trifluoromethylcopper to form pentafluoroethylcopper.This then reacts with aryl halide to give pentafluoroethyl compounds.Perfluoroalkylcopper is thermally cleaved to perfluoroalkyl radical, which then reacts with pyridine to give perfluoroalkylpyridines.This mechanism must be involved in the formation of 2,3-bis(trifluoromethyl)benzofuran.Introduction of a perfluoroalkyl group to the position originally unoccupied with halogen might be due to the rather localized double bond in benzofuran.
- Kobayashi, Yoshiro,Kumadaki, Itsumaro
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p. 661 - 664
(2007/10/02)
-